CA2169398A1 - Tuned intake manifold for otto cycle engines - Google Patents
Tuned intake manifold for otto cycle enginesInfo
- Publication number
- CA2169398A1 CA2169398A1 CA002169398A CA2169398A CA2169398A1 CA 2169398 A1 CA2169398 A1 CA 2169398A1 CA 002169398 A CA002169398 A CA 002169398A CA 2169398 A CA2169398 A CA 2169398A CA 2169398 A1 CA2169398 A1 CA 2169398A1
- Authority
- CA
- Canada
- Prior art keywords
- plenum
- branch
- conduits
- runner
- cylinders
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Abandoned
Links
Classifications
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02M—SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
- F02M35/00—Combustion-air cleaners, air intakes, intake silencers, or induction systems specially adapted for, or arranged on, internal-combustion engines
- F02M35/10—Air intakes; Induction systems
- F02M35/10091—Air intakes; Induction systems characterised by details of intake ducts: shapes; connections; arrangements
- F02M35/10131—Ducts situated in more than one plane; Ducts of one plane crossing ducts of another plane
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02B—INTERNAL-COMBUSTION PISTON ENGINES; COMBUSTION ENGINES IN GENERAL
- F02B27/00—Use of kinetic or wave energy of charge in induction systems, or of combustion residues in exhaust systems, for improving quantity of charge or for increasing removal of combustion residues
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02B—INTERNAL-COMBUSTION PISTON ENGINES; COMBUSTION ENGINES IN GENERAL
- F02B27/00—Use of kinetic or wave energy of charge in induction systems, or of combustion residues in exhaust systems, for improving quantity of charge or for increasing removal of combustion residues
- F02B27/005—Oscillating pipes with charging achieved by arrangement, dimensions or shapes of intakes pipes or chambers; Ram air pipes
- F02B27/006—Oscillating pipes with charging achieved by arrangement, dimensions or shapes of intakes pipes or chambers; Ram air pipes of intake runners
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02M—SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
- F02M35/00—Combustion-air cleaners, air intakes, intake silencers, or induction systems specially adapted for, or arranged on, internal-combustion engines
- F02M35/10—Air intakes; Induction systems
- F02M35/10006—Air intakes; Induction systems characterised by the position of elements of the air intake system in direction of the air intake flow, i.e. between ambient air inlet and supply to the combustion chamber
- F02M35/10026—Plenum chambers
- F02M35/10052—Plenum chambers special shapes or arrangements of plenum chambers; Constructional details
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02M—SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
- F02M35/00—Combustion-air cleaners, air intakes, intake silencers, or induction systems specially adapted for, or arranged on, internal-combustion engines
- F02M35/10—Air intakes; Induction systems
- F02M35/10006—Air intakes; Induction systems characterised by the position of elements of the air intake system in direction of the air intake flow, i.e. between ambient air inlet and supply to the combustion chamber
- F02M35/10072—Intake runners
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02M—SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
- F02M35/00—Combustion-air cleaners, air intakes, intake silencers, or induction systems specially adapted for, or arranged on, internal-combustion engines
- F02M35/10—Air intakes; Induction systems
- F02M35/104—Intake manifolds
- F02M35/112—Intake manifolds for engines with cylinders all in one line
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
- Y02T10/00—Road transport of goods or passengers
- Y02T10/10—Internal combustion engine [ICE] based vehicles
- Y02T10/12—Improving ICE efficiencies
Landscapes
- Engineering & Computer Science (AREA)
- Chemical & Material Sciences (AREA)
- Combustion & Propulsion (AREA)
- Mechanical Engineering (AREA)
- General Engineering & Computer Science (AREA)
- Physics & Mathematics (AREA)
- Geometry (AREA)
- Output Control And Ontrol Of Special Type Engine (AREA)
- Cylinder Crankcases Of Internal Combustion Engines (AREA)
Abstract
A tuned intake manifold is provided for OTTO cycle engines and includes a plenum having an aperture through which a gaseous fuel mixture can be received.
First and second branch openings are disposed at opposite points across the plenum, with respective first and second branch conduits connected thereto. Each branch conduit divides into a plurality of runner conduits all terminating at a head flange.
The various gaseous paths, each defined by one of the branch conduits and one of the runner conduits, have substantially the same length, substantially the same volume, and substantially the same radius and arc-length of curvature.
First and second branch openings are disposed at opposite points across the plenum, with respective first and second branch conduits connected thereto. Each branch conduit divides into a plurality of runner conduits all terminating at a head flange.
The various gaseous paths, each defined by one of the branch conduits and one of the runner conduits, have substantially the same length, substantially the same volume, and substantially the same radius and arc-length of curvature.
Description
TUNED INTAKE MANIFOLD FOR OTTO CYCLE ENGINES
This invention relates to tuned intake manifolds for OTTO cycle engines, and has to do particularly within an improvement to such manifolds in order to provide better distribution of fuel with improved flow and flow stability, and more effective 5 tuning.
BACKGROUND OF THIS INVENTION
The overwhelming majority of vehicles use Otto-cycle (throttled, spark-ignited) engines. Such engines may be fueled by gasoline, natural gas, liquefied petroleum gas (LPG), alcohol, or propane. In the U.S. over 175 Million vehicles use Otto cycle 10 engines.
Otto-cycle engines control engine air col~u~ )tion with a throttle. Air flows past the throttle, through the intake manifold, and on to the cylinder head. Themanifold has four primary purposes, as noted below:
1. to m~ximi7~ airflow into the engine 2. to equally distribute up to five fluids to each cylinder - intake air - idle by-pass air - fuel - Positive Cr~nl~ e Ventilation (PCV) gases - Fxh~llct Gas Recirculation (EGR) gases 3. to provide adequate air/fuel mixing 4. to add enough heat to ~apolize the fuel.
While OTTO-cycle engines have been developed and improved over many years, there remains room for improvement, particularly in connection with the 25 distribution of fuel to the cylinders and to improving fuel-flow contour.
GENERAL DESCRIPTION OF THIS INVENTION
The present invention uses a m~rk~lly dirr~lel~ concept to route fluids from the manifold's central plenum into the individual runner conduits. The new method groups the manifold runner conduits into pairs that mirror the engine's bl~alhillg 30 sequence (e.g. 1-4 and 3-2 in the case of four cycle, in-line engines). A particular design of the plenum has the result that airflow into the individual runner conduits is alternately drawn from opposite sides of the plenum. This flow phasing may be -referred to as symmetrical and synchronous. The symmetrical hal.lwale geometry utilized has several inherent characteristics which favour the four primary purposes of the manifold, these characteristics being:
- good distribution - stable flow - effective tuning - equal heating of all runners The present concept is particularly beneficial in 4 and 6 cylinder engines which have independent intake ports and which use throttle body fuel introduction (TBI). However, it is also applicable to engines with siamese intake ports, to engines with any number of cylinders, to vee-type engines, horizontally opposed engines, and to engines using multi-point fuel injection (MPI). In order to simplify this discussion, a 4-cylinder engine with independent intake ports and throttle body fuel injection will be used as the comparison model.
By comparison, conventional intake manifold designs group the runners into pairs that mimic the engine's physical layout (e.g. 1-2 and 3-4). As a result, the airflow into the individual runners is drawn twice from each side of the plenum before alL~ ling to the opposite side. The conventional design is thus prone to lower airflow, greater turbulence, lower flow stability and poorer distribution. The resulting asymmetrical geometry also tends to cause unequal heating of the individual manifold runners.
Intake manifolds often perform peripheral, mech~nic~l functions which are not relevant to engine performance. Such peripherals include: bracing or mounting ofaccessories (alternator, etc.); mounting of throttle linkage mech~ni~m~; sourcing of manifold vacuum to various servos (brake booster, etc.). These mechanical functions are not influenced by this design and need not be discussed further.
More particularly, this invention provides a tuned intake manifold for Otto cycle engines, comprising:
a plenum, an apellule in the plenum through which the plenum can receive a gaseous fuel mixture, first and second branch opel~ings into the plenum, the openings being disposed in substantial opposition to each other across the plenum, first and second branch conduits co~ ating with said first and second branch openings respectively, each branch conduit di~ icalillg into a plurality of runner conduits all of 5 which termin~te at their connections to a head flange; the various gaseous paths, each defined by one of the branch conduits and one of the runner conduits into which the branch conduit divaricates, all having subst~nti~lly the same length beginning at the plenum, substantially the same volume, and substantially the same radius and arc-length of curvature.
Further, this invention provides a method for delivering a gaseous fuel mixture to the cylinders of an engine, having at least four in-line cylinders, the number of cylinders being even, comprising:
receiving the lllLl~lurc in a plenum through an apcllulc, passing the l~ lule out of the plenum through first and second branch openings disposed in substantial opposition to each other across the plenum, passing the mixture into first and second branch conduits cnlll"~u~-icating withsaid first and second branch openings respectively, each branch conduit divaricating into a plurality of runner conduits all of which terrnin~te at their connections to the engine; and el~u~ g that the various gaseous paths, each defined by one of the branch conduits and one of the runner conduits into which the branch conduit divaricates, all have subst~nti~lly the same length begh~ g at the plenum, substantially the samevolume, and subst~nti~lly the same radius and arc-length of ~;ul~Lulc.
GENERAL DESCRIPTION OF THE DRAVVINGS
One embodiment of this invention is illustrated in the accolllpal.ying drawings,in which like numerals denote like parts throughout the several views and in which:
Figures 1, 2 and 3 illustrate perspective views, taken from dirrel~l~l angles, of an intake manifold constructed in accordance with this invention;
Figure 4 is a schematic top view of the intake manifold of this invention;
Figure 5 is a schematic drawing, in elevation, showing the dirr~,lel.L vertical positions of components;
Figures 6a, 6b and 6c are schematic drawings illustrating dirrerc~ possibilities for adding heat to the plenum and optionally to the runner conduits carrying fuel mixture to the cylinders;
Figure 7 is a partly broken-away, perspective view of an intake manifold constructed in accordance with this invention, and provided with jacket-heating means 5 in order to ensure that liquid fuel will be vaporized;
Figure 8 is a srllpm~tic top plan view of an intake manifold in accordance with this invention, illustrating the engine breathing order;
Figure 9 is a further sc-hPn~ti~ view in top plan, showing the gaseous flow within the plenum when fuel is being directed to a particular cylinder;
Figures 10a to 10e are graphs illustrating the superiority of the present intakemanifold, in terms of specific power;
Figures lla, llb and 11c illustrate the breathing differences between the different manifold types, Figures 11b and 11c represçnting the prior art;
Figures 12a to 12d are graphic representations of the dirrelelll breathing 15 characteri~tics of the three manifold types; and Figures 13a, 13b and 13c illustrate the sources of peak fuel flow, colllpalillg the present invention (Figure 13c) with the prior art (Figures 13a and 13b).
DETAILED DESCRIPTION OF THE DRAVVINGS
Attention is directed to Figures 1 through 4, which show various views of the 20 intake manifold in accordance with this invention. In Figure 4, the followingcomponents and parts are identified by number. A central cylindrical plenum 1 has an apellule, typically an axial al~llul~, through which the plenum can receive agaseous fuel mixture from a fuel Lhlolllillg device. The aperture is seen in Figures 1-3, but not in the sch~m~tic drawing of Figure 4. Figure 4 does illustrate, however, 25 first and second branch openings 2 and 3 which are disposed in substantial opposition to each other across a diameter of the cylindrical plenum 1. First and second branch conduits 2a and 3a, co-l-lllun-cate with the ~lrst and second branch openings 2 and 3 respectively. As can be especially seen in Figure 4, each branch conduit 2a, 3a divaricates into two runner conduits 4, 5 and 10, 11, respectively, and all of the 30 runner conduits terminate at their connections to a head flange 16. The locations of divarication (birul~;alion in this case) are m~rke(l by numerals 17 and 18 in Figure 4.
Other components illustrated in Figure 4 are set forth in the table below, in order to 21693~
avoid needless repetition.
Fi~ure 4 Reference Points Cyl Cyl Cyl Cyl Manifold Feature 1 _ 3 Plenum Branch opening ~ 3---- ----2----Runner conduit cross-section area 11 10 4 5 Transition section area 13 12 6 7 Port cross-section area 15 14 8 9 Cylinder head flange 16 Using the airflow into cylinder 1 as an example, air would flow through the plenum 1, to the branch conduit 3a, then on to the runner conduit 11, which connects 15 to transition section area 13, the latter ~sllming the port cross-section area at 15, and then te~ ting at the head flange 16.
As already mentioned, the plenum 1 is preferably cylindrical and coaxial with the throttle bore. The plenum volume and height are consistent with conventionalpractice and are expected to promote good mixing while ll~ini~ g the pressure drop 20 caused by turning the airflow 90 as it enters the branch conduits 2a and 3a. A
review of three high volume manifolds reveals plenum volumes ranging from 9.8%
to 27.5% of the engine swept volume. The test manifold used herein represented 9.8% of the engine swept volume, and was quite successful.
The plenum 1 is the ~lerelled location to ensure fuel vaporization.
25 Conventional practice is also applicable here. That is, a depression in the floor of the plenum (or a raised ch~;ulllf~ llial lip at the plenum's exit points) would capture any liquid fuel and retain it until it vaporized. The depth of the depression (or height of a lip) would be based on conventional practice. The heat of vaporization could come from a number of optional sources including: a coolant jacket SUll~ undillg the plenum 30 (used in our test piece); an electric heater installed in the floor of the manifold;
exhaust directed against the floor of the manifold (an approach no longer used in North American engines); or, exhaust gas recirculation (EGR) into the plenum area.
216939~
The plcfellcd embodiment has the plenum floor horizontal and parallel to the throttle body flange (Figure 5).
Almost all engines have an "as installed" power angle (P / ), which is the angle between the horizontal center line of the cr~nk~h~ft and true hori_ontal. Many engines also have a tilt angle (T / ), which is the angle between the vertical center line of the engine and true vertical. Both P / and T / are commonly in the rangeof 5 to 15. The preferred embodiment would accommodate the engine's angularity(P ~ and T / ) by adjusting the arc of the runners. That approach was used in our test part and is visible in Figures 1, 2, and 3. Figure 5 is a 2-D partial projection illustrating a hori_ontal plenum floor to be connPctecl by the runner conduits (not shown) to the cylinder head flange which has a 15 P / . Notably, the runners all slope downhill from the plenum to the cylinder head flange.
Air from the plenum 1 alternately flows into branch conduits 2a and 3a. In the plcfcllcd embodiment, the branch conduits are cylindrical, although rectangular or other cross-sections can be used. In the plcr~lrcd embodiment, both branch conduits 2a and 3a are equally si_ed (shape, length, and volume), equally spaced from the centre line of the plenum (throttle), and equally angled from the floor of the plenum. Again in the plercl,cd embodiment, both branch conduits are either levelor tilt dowllw~lds toward the cylinder head.
The cross-sectional area of the branches is chosen to m~ximi7e airflow and is based on conventional practice.
As shown in Figure 4, runner conduits 4 and 5 intersect at jullcLulc 17, which is the end of the branch conduit 2a. Similarly, the runner conduits 10 and 11 intersect at juncture 18, which is the end of the branch conduit 3a. In the plefellcd embodiment, the runner intersection points 17 and 18 lie within the same vertical plane as the vertical axis of the cylindrical plenum 1.
As can be seen in Figure 4, the lengths and volumes of all four runner conduits 4, 5, 10 and 11 are preferably subst~nti~lly identical. Also, the curvilinear portions of the runner conduits lc~lcselll generally the same arc-length of curvature, and have substantially the same radius. In the p~rellcd embodiment, all runner conduits are level and slope "downhill" from the branch junctures 17 and 18 to the manifold flange 16. As noted above, the engine's P / and T / are accommodated by adjusting the runner conduit geometries. That accommodation can be accomplished, while m~int~ining equal runners lengths and volumes, by any or all of the following means: adjusting bend radii and locations; moving the location of the plenum (for-aft and side-side); adjusting the angle between the center line of the runner conduits (at 8, 9, 14, 15) and the vertical plane of the flange 16 (eg., the angle might be 95 instead of the conventional 90 if the T / = -5).
As in-lic~tP~, this invention is intended to be a tuned design. The general appearance, as shown in Figures l, 2, and 3, illustrates the physical geometry needed to achieve typical tuning speeds. That is, it is nPces~ry to bring the plenum relatively close to the cylinder head in order to get the total volumes and lengths small enough to put the first tuning frequency in the 4000-5000 rpm range on a 4-cylinder engine. The ploto~y~e manifold ~ecignP(l for a high volume 2.5L 4-cylinder engine had a first tuning speed of 4000 rpm. One equation to calculate the tuning speed is as follows:
N_ =(30-a/2~)-{[(A-B+A+ 1)_(A-B+A+ 1)2-4A-B]/[2-A-B-Ll-Cl]}0.5 Where:
N+=tuned engine speeds A=(l2-A~ l-A2) Al=cross sectional area of runner ll=rli~t~nre from intake valve to plenum A2=cross sectional area of plenum 12=~i.ct~nr-e from plenum to throttle body inlet B=C2/Cl Cl =Veff=D-(CR+ 1)/[2-(CR-l)]
D=displacement per cylinder CR.=co~ ssion ratio C~=volume from throttle body inlet to intake valve (ll-Al) a=speed of sound in air (mixture) Ll = ll-Al ~sllmP-s runners are of approximately equal length and volume adapted from Heywood, 1988, p.312-313.
In the lowest cost embodiment, manifold heating is provided by an engine coolant jacket. Notably, only enough heat should be added to vaporize any residual liquid fuel. Any heat above that amount merely increases the intake charge temperature, reducing its peak power output. Accordingly, the trend is to minimi7f manifold heating. Figures 6a, 6b, and 6c depict three options for the coolant jacket 5 approach to heating the plenum. Figure 6a shows a Illi~illllllll approach wherein the coolant jacket ~ulloullds the vertical portion of the plenum (19) and also underlies the floor of the plenum (20). Figure 6b shows an option wherein the jacket is extended to also include the floor (22) and vertical wall portions (21) of the branches. Figure 6c shows an extreme case where the coolant jacket also extends beneath the floor10 portion (23) of the runners for their entire length. Figure 7 provides a 3-D cross sectional view of the plenum heating concept from Figure 6a.
As an ~lle..lAIive to coolant heating, electric heating is possible. Both Texas lulllelll~ and GTE Sylvania have produced PTC (positive telllpeldLul~ coefficient) heaters for automotive use. Such heaters typically consist of an electrically heated al lmin-lm body which is mounted in the floor of the manifold casting and is at least partially thermally isolated from the casting by g~ ting or other in~lllAtQr means.
Such devices have had in-rush power levels > 700 watts and quiescent power levels > 170 watts. PTC heaters, although more e~el~iv~, can have source telllpeldlul~sof 175C, and thus are excellent ~ IIIAI;V~S for assuring fuel vaporization.
A fundamental feature of this invention is the staging of airflow out of the plenum and into the runner conduits. Consider that the plenum has a left (L) andright (R) half as shown in Figure 8. Also note that most 4-cylinder engines have a firing order, and hence a breathing sequence, of 1-3-4-2. Thus, the air will flow out of the plenum in the following sequence: L-R-L-R. Hence, the flow symmetrically switches back and forth between the two sides of the plenum, at the same frequency as the intake pulses occur. For purposes of illustrating the concept, the firing order 1-34-2 is used in the following examples. However, the concept also applies to the less frequently used firing order 1-2-4-3.
It is also worthwhile to note the sources of peak, i~l~lA~ ous intake flow.
Figure 9 graphically depicts the sources of peak airflow, showing the condition where Cylinder 2 is bl~,alllillg and the other three cylinders have closed intake valves. Peak flow (26) is composed of the main airflow (24) coming past the throttle, plus stored -air (25) that is released from the dead-headed runner conduits (i.e. runner conduits conn~ctecl to cylinders with closed intake valves). Two points are notable. Firstly, the vectors of the various flow components all tend to be in the direction of enhancing airflow into the active runner conduit, and creating only modest turbulence.
5 Secondly, since the manifold is symmetrical, identical vector condition exists regardless of which cylinder is b~ea~ g (i.e. while vectors are mirror images, their amplitudes and relative relationships are unchanged). Thus, this concept is particularly stable and prone to equal distribution.
TEST RESULTS
An intake manifold in accordance with this invention has been designed, cast, and tested on a production 2.5L, 4-cylinder TBI engine. Air-fuel distribution was measured at 54 speed-load points and wide open throttle power measured at 17 points (2000 to 5200 rpm), with two air cleaner configurations. The manifold in accordance with this invention provided more power, at all speeds, than the original equipment 15 manifold. The data from those tests, along with the design features of the present invention, are co,l~aled to conventional manifold designs in the discussion below.
Specifically, the intake manifold of this invention is compared to two conventional manifold design styles as used on three production engines. The two conventional design styles are referred to as TRI-Y manifolds (two reviewed) and 4-20 LEG manifolds (one reviewed). The table below co",p~,~s manifold features. It is notable that all used throttle body fuel injection and were offered on recent, high volume North American 4-cylinder engines.
Pro~h~ti~n Fn~n~ ~ Manifold Details M~mlfaçtllrer General MotorsFord Chrysler Part No. 10124608RF-E7EE-9425-JC 4621360 Engine size(cc's) 25001 2500' 1900 2200 Power (~rpm) ~ +5% 92 ~ 440088 ~ 4400 93 ~ 5200 30 Specific Power (BHP/L) 36.8 46.3 42.3 Plenum:Vol (cc's) 246 246 254 604 21 G~39~
Plenum:Eng.Vol 9.8% 9.8% 13.4% 27.5%
Manifold Vol (cc's) 1594 1220 700 1040 Manifold:Eng.Vol 63.8% 48.8% 36.8% 47.3%
Runner Conduits Lengths: 1 12.5 5.0 6.13 4.0 (ininches) 2 12.5 5.0 3.38 4.5 3 12.5 5.0 3.38 4.5 4 12.5 5.0 6.13 4.0 Runner Conduit Equivalent Dia.
(in) 1.445 1.445 1.37 1.641 Runner Vol.(cc's) 1348 522 446 436 Notel: same 2500 cc engine As can be seen, the size of the runner conduits, plenums and overall manifolds varied signifi~ntly, in both absolute terms and as pelcelllage of engine swept volume (36.8% to 48.8%). Specific power output also varied widely (36.8 to 46.3 BHP/L).However, as can be seen from the curves shown in Figures lOa through lOe, there is no obvious correlation between intake manifold design factors and specific power 20 output. The exception is that use of the present design produced higher specific power output. The characteristics plotted in Figure 10 are as follows:
Figure Feature Plotted versus BHP/L
Figure lOa Manifold Volume + Engine Volume Figure lOb Plenum Volume + Engine Volume 25Figure lOc Runner Volume + Engine Volume Figure lOd Runner Conduit Length Figure lOe Equivalent Runner Diameter Although the data sample is ~-lmitte(1ly quite limit~d, the curves in Figure 10 in(lic~te that conventional manifold design features have no obvious, strong 30 correlation with specific power output. In fact, one would expect specific power output to show a strong correlation with other factors such as c~m~h~ft lift, c~m~h~ft event duration, c~m~h~ft overlap, peak power rpm, intake valve size, number of 216939~
intake valves, and compression ratio. Notably, while the present manifold's design feature did not seem to fit any possible trends from these three engines, it did produce more power. The obvious suggestion is that the present design approach is fundamentally dirr~lclll.
Simplified, 2-D top views of the three manifold designs are provided in Figures 1 la to 11c. All are shaded to identify left and right halves of the manifolds.
These views help illustrate the blcaLl~illg dirrelcl~es between the manifold types.
Notably, conventional manifolds pair cylinders 1-2 and 3-4 together, while the present manifold pairs 1-4 and 3-2 together. The dirr~lcl1ces in cylinder pairings results in dirrerellL bledLhillg phasings (i.e. the sequence of gases leaving the plenum) as is summarized in the following table:
Airflow to in~ Cyl No.
is drawn from the 1 ~..ul.~'s Left (L) Right (R) Rç~-llt~nt rl~nu"~
Manifold Type Sector Sector Bre~thin~ Order INVENTION 1,4 3,2 L-R-L-R
TRI-Y 1,2 3,4 L-R-R-L
4-LEG 1,2 3,4 L-R-R-L
The plenum breathing characteristics of the three manifold types are graphically portrayed in Figures 12a, 12b, 12c and 12d. They depict the relativelocation of the mass airflow out of the plenums versus engine position (in number of revolutions). Theflow location axes are gra(l~l~te~l from Left to Right, with the full scale span representing a 180 change in angular location (the 0 2 180 line defines the throttle plate centerline). While the graphs are based on a simplified model of engine bleaLlling, they inrlic~te the relative sequencing of manifold ble~Llling.
For r~fe~ ce purposes, Figure 12a shows that four intake pulses occur every two engine revolutions. Figure 12b illustrates that the present manifold's plenum has a symmetrical breathing sequence which switches sides (L-R-L-R-...) synchronously 30 with the engine's breathing sequence (1-3-4-2). By comparison, the TRI-V
manifold's b~Llling sequence (Figure 12c) is symmetrical, but switches sides at half the synchronous rate (i.e., every other intake pulse). The 4-LEG manifold's 21693g~
b,eaLhil1g sequence (Figure 12d), while superficially symmetrical (R-R-L-L-R-R-L-L-...) has flow occurring from four different angular locations and is more accurately labelled as asymmetrical. The symmetrical and synchronous nature of the present manifold breathing sequence are considered to increase stability and tuning efficiency.
The present design is also regarded as being superior at sourcing a portion of its peak in~t~nt~nPous flow from the dead-headed runner conduits. The sources ofpeak flow are illustrated in Figures 13a, 13b, and 13c. In the case of the TRI-Ymanifold (Figure 13a), dead-headed gases from cylinders 3 and 4 (29,28) combine to reinforce the main air flow past the throttle (24), which is then partially opposed by the gas from de~dhP~ded cylinder 1 (27). In the case of the 4-LEG manifold (Figure 13b), dead-headed gases from cylinders 1 and 3 (27,29) primarily oppose the mainair flow past the throttle (24), while the gas from dead-headed cylinder 4(28) primarily ~cillro~;es the main flow (24). In the case of the present design (Figure 13c), dead-headed gases from cylinders 1 and 4 (27,28) combine to reinforce the main air flow past the throttle (24), which is then malgil~lly reinforced by the gas from ~e~dhPaded cylinder 3 (29).
While turbulence is desirable from the standpoint of causing the air and fuel to mix, it is undesirable as it causes flow losses. Accordingly, intake manifolds must balance turbulence and airflow. The present manifold is deemed to offer a lower and particularly stable amount of turbulence which can be adjusted by the geometry of the individual design (e.g., convergence angle of the runner at the branch junc~ulcS 17 and 18).
By comparison, the conventional designs tend to have the flow from one or more of the d~P~llhe~d~Pd runner conduits m~rke-lly opposing the flow into the active runner conduit. While this opposition may create turbulence which assists in mixing, it would also act to reduce the manifold's flow efficiency.
While one embodiment of this invention has been illustrated in the acco",pa,lyillg drawings, and described hereinabove, it will be evident to those skilled in the art that changes and modifications may be made therein without departing from the essence of this invention, as set forth in the appended claims.
1~9 ~a~ 1 3 IS ~ c
This invention relates to tuned intake manifolds for OTTO cycle engines, and has to do particularly within an improvement to such manifolds in order to provide better distribution of fuel with improved flow and flow stability, and more effective 5 tuning.
BACKGROUND OF THIS INVENTION
The overwhelming majority of vehicles use Otto-cycle (throttled, spark-ignited) engines. Such engines may be fueled by gasoline, natural gas, liquefied petroleum gas (LPG), alcohol, or propane. In the U.S. over 175 Million vehicles use Otto cycle 10 engines.
Otto-cycle engines control engine air col~u~ )tion with a throttle. Air flows past the throttle, through the intake manifold, and on to the cylinder head. Themanifold has four primary purposes, as noted below:
1. to m~ximi7~ airflow into the engine 2. to equally distribute up to five fluids to each cylinder - intake air - idle by-pass air - fuel - Positive Cr~nl~ e Ventilation (PCV) gases - Fxh~llct Gas Recirculation (EGR) gases 3. to provide adequate air/fuel mixing 4. to add enough heat to ~apolize the fuel.
While OTTO-cycle engines have been developed and improved over many years, there remains room for improvement, particularly in connection with the 25 distribution of fuel to the cylinders and to improving fuel-flow contour.
GENERAL DESCRIPTION OF THIS INVENTION
The present invention uses a m~rk~lly dirr~lel~ concept to route fluids from the manifold's central plenum into the individual runner conduits. The new method groups the manifold runner conduits into pairs that mirror the engine's bl~alhillg 30 sequence (e.g. 1-4 and 3-2 in the case of four cycle, in-line engines). A particular design of the plenum has the result that airflow into the individual runner conduits is alternately drawn from opposite sides of the plenum. This flow phasing may be -referred to as symmetrical and synchronous. The symmetrical hal.lwale geometry utilized has several inherent characteristics which favour the four primary purposes of the manifold, these characteristics being:
- good distribution - stable flow - effective tuning - equal heating of all runners The present concept is particularly beneficial in 4 and 6 cylinder engines which have independent intake ports and which use throttle body fuel introduction (TBI). However, it is also applicable to engines with siamese intake ports, to engines with any number of cylinders, to vee-type engines, horizontally opposed engines, and to engines using multi-point fuel injection (MPI). In order to simplify this discussion, a 4-cylinder engine with independent intake ports and throttle body fuel injection will be used as the comparison model.
By comparison, conventional intake manifold designs group the runners into pairs that mimic the engine's physical layout (e.g. 1-2 and 3-4). As a result, the airflow into the individual runners is drawn twice from each side of the plenum before alL~ ling to the opposite side. The conventional design is thus prone to lower airflow, greater turbulence, lower flow stability and poorer distribution. The resulting asymmetrical geometry also tends to cause unequal heating of the individual manifold runners.
Intake manifolds often perform peripheral, mech~nic~l functions which are not relevant to engine performance. Such peripherals include: bracing or mounting ofaccessories (alternator, etc.); mounting of throttle linkage mech~ni~m~; sourcing of manifold vacuum to various servos (brake booster, etc.). These mechanical functions are not influenced by this design and need not be discussed further.
More particularly, this invention provides a tuned intake manifold for Otto cycle engines, comprising:
a plenum, an apellule in the plenum through which the plenum can receive a gaseous fuel mixture, first and second branch opel~ings into the plenum, the openings being disposed in substantial opposition to each other across the plenum, first and second branch conduits co~ ating with said first and second branch openings respectively, each branch conduit di~ icalillg into a plurality of runner conduits all of 5 which termin~te at their connections to a head flange; the various gaseous paths, each defined by one of the branch conduits and one of the runner conduits into which the branch conduit divaricates, all having subst~nti~lly the same length beginning at the plenum, substantially the same volume, and substantially the same radius and arc-length of curvature.
Further, this invention provides a method for delivering a gaseous fuel mixture to the cylinders of an engine, having at least four in-line cylinders, the number of cylinders being even, comprising:
receiving the lllLl~lurc in a plenum through an apcllulc, passing the l~ lule out of the plenum through first and second branch openings disposed in substantial opposition to each other across the plenum, passing the mixture into first and second branch conduits cnlll"~u~-icating withsaid first and second branch openings respectively, each branch conduit divaricating into a plurality of runner conduits all of which terrnin~te at their connections to the engine; and el~u~ g that the various gaseous paths, each defined by one of the branch conduits and one of the runner conduits into which the branch conduit divaricates, all have subst~nti~lly the same length begh~ g at the plenum, substantially the samevolume, and subst~nti~lly the same radius and arc-length of ~;ul~Lulc.
GENERAL DESCRIPTION OF THE DRAVVINGS
One embodiment of this invention is illustrated in the accolllpal.ying drawings,in which like numerals denote like parts throughout the several views and in which:
Figures 1, 2 and 3 illustrate perspective views, taken from dirrel~l~l angles, of an intake manifold constructed in accordance with this invention;
Figure 4 is a schematic top view of the intake manifold of this invention;
Figure 5 is a schematic drawing, in elevation, showing the dirr~,lel.L vertical positions of components;
Figures 6a, 6b and 6c are schematic drawings illustrating dirrerc~ possibilities for adding heat to the plenum and optionally to the runner conduits carrying fuel mixture to the cylinders;
Figure 7 is a partly broken-away, perspective view of an intake manifold constructed in accordance with this invention, and provided with jacket-heating means 5 in order to ensure that liquid fuel will be vaporized;
Figure 8 is a srllpm~tic top plan view of an intake manifold in accordance with this invention, illustrating the engine breathing order;
Figure 9 is a further sc-hPn~ti~ view in top plan, showing the gaseous flow within the plenum when fuel is being directed to a particular cylinder;
Figures 10a to 10e are graphs illustrating the superiority of the present intakemanifold, in terms of specific power;
Figures lla, llb and 11c illustrate the breathing differences between the different manifold types, Figures 11b and 11c represçnting the prior art;
Figures 12a to 12d are graphic representations of the dirrelelll breathing 15 characteri~tics of the three manifold types; and Figures 13a, 13b and 13c illustrate the sources of peak fuel flow, colllpalillg the present invention (Figure 13c) with the prior art (Figures 13a and 13b).
DETAILED DESCRIPTION OF THE DRAVVINGS
Attention is directed to Figures 1 through 4, which show various views of the 20 intake manifold in accordance with this invention. In Figure 4, the followingcomponents and parts are identified by number. A central cylindrical plenum 1 has an apellule, typically an axial al~llul~, through which the plenum can receive agaseous fuel mixture from a fuel Lhlolllillg device. The aperture is seen in Figures 1-3, but not in the sch~m~tic drawing of Figure 4. Figure 4 does illustrate, however, 25 first and second branch openings 2 and 3 which are disposed in substantial opposition to each other across a diameter of the cylindrical plenum 1. First and second branch conduits 2a and 3a, co-l-lllun-cate with the ~lrst and second branch openings 2 and 3 respectively. As can be especially seen in Figure 4, each branch conduit 2a, 3a divaricates into two runner conduits 4, 5 and 10, 11, respectively, and all of the 30 runner conduits terminate at their connections to a head flange 16. The locations of divarication (birul~;alion in this case) are m~rke(l by numerals 17 and 18 in Figure 4.
Other components illustrated in Figure 4 are set forth in the table below, in order to 21693~
avoid needless repetition.
Fi~ure 4 Reference Points Cyl Cyl Cyl Cyl Manifold Feature 1 _ 3 Plenum Branch opening ~ 3---- ----2----Runner conduit cross-section area 11 10 4 5 Transition section area 13 12 6 7 Port cross-section area 15 14 8 9 Cylinder head flange 16 Using the airflow into cylinder 1 as an example, air would flow through the plenum 1, to the branch conduit 3a, then on to the runner conduit 11, which connects 15 to transition section area 13, the latter ~sllming the port cross-section area at 15, and then te~ ting at the head flange 16.
As already mentioned, the plenum 1 is preferably cylindrical and coaxial with the throttle bore. The plenum volume and height are consistent with conventionalpractice and are expected to promote good mixing while ll~ini~ g the pressure drop 20 caused by turning the airflow 90 as it enters the branch conduits 2a and 3a. A
review of three high volume manifolds reveals plenum volumes ranging from 9.8%
to 27.5% of the engine swept volume. The test manifold used herein represented 9.8% of the engine swept volume, and was quite successful.
The plenum 1 is the ~lerelled location to ensure fuel vaporization.
25 Conventional practice is also applicable here. That is, a depression in the floor of the plenum (or a raised ch~;ulllf~ llial lip at the plenum's exit points) would capture any liquid fuel and retain it until it vaporized. The depth of the depression (or height of a lip) would be based on conventional practice. The heat of vaporization could come from a number of optional sources including: a coolant jacket SUll~ undillg the plenum 30 (used in our test piece); an electric heater installed in the floor of the manifold;
exhaust directed against the floor of the manifold (an approach no longer used in North American engines); or, exhaust gas recirculation (EGR) into the plenum area.
216939~
The plcfellcd embodiment has the plenum floor horizontal and parallel to the throttle body flange (Figure 5).
Almost all engines have an "as installed" power angle (P / ), which is the angle between the horizontal center line of the cr~nk~h~ft and true hori_ontal. Many engines also have a tilt angle (T / ), which is the angle between the vertical center line of the engine and true vertical. Both P / and T / are commonly in the rangeof 5 to 15. The preferred embodiment would accommodate the engine's angularity(P ~ and T / ) by adjusting the arc of the runners. That approach was used in our test part and is visible in Figures 1, 2, and 3. Figure 5 is a 2-D partial projection illustrating a hori_ontal plenum floor to be connPctecl by the runner conduits (not shown) to the cylinder head flange which has a 15 P / . Notably, the runners all slope downhill from the plenum to the cylinder head flange.
Air from the plenum 1 alternately flows into branch conduits 2a and 3a. In the plcfcllcd embodiment, the branch conduits are cylindrical, although rectangular or other cross-sections can be used. In the plcr~lrcd embodiment, both branch conduits 2a and 3a are equally si_ed (shape, length, and volume), equally spaced from the centre line of the plenum (throttle), and equally angled from the floor of the plenum. Again in the plercl,cd embodiment, both branch conduits are either levelor tilt dowllw~lds toward the cylinder head.
The cross-sectional area of the branches is chosen to m~ximi7e airflow and is based on conventional practice.
As shown in Figure 4, runner conduits 4 and 5 intersect at jullcLulc 17, which is the end of the branch conduit 2a. Similarly, the runner conduits 10 and 11 intersect at juncture 18, which is the end of the branch conduit 3a. In the plefellcd embodiment, the runner intersection points 17 and 18 lie within the same vertical plane as the vertical axis of the cylindrical plenum 1.
As can be seen in Figure 4, the lengths and volumes of all four runner conduits 4, 5, 10 and 11 are preferably subst~nti~lly identical. Also, the curvilinear portions of the runner conduits lc~lcselll generally the same arc-length of curvature, and have substantially the same radius. In the p~rellcd embodiment, all runner conduits are level and slope "downhill" from the branch junctures 17 and 18 to the manifold flange 16. As noted above, the engine's P / and T / are accommodated by adjusting the runner conduit geometries. That accommodation can be accomplished, while m~int~ining equal runners lengths and volumes, by any or all of the following means: adjusting bend radii and locations; moving the location of the plenum (for-aft and side-side); adjusting the angle between the center line of the runner conduits (at 8, 9, 14, 15) and the vertical plane of the flange 16 (eg., the angle might be 95 instead of the conventional 90 if the T / = -5).
As in-lic~tP~, this invention is intended to be a tuned design. The general appearance, as shown in Figures l, 2, and 3, illustrates the physical geometry needed to achieve typical tuning speeds. That is, it is nPces~ry to bring the plenum relatively close to the cylinder head in order to get the total volumes and lengths small enough to put the first tuning frequency in the 4000-5000 rpm range on a 4-cylinder engine. The ploto~y~e manifold ~ecignP(l for a high volume 2.5L 4-cylinder engine had a first tuning speed of 4000 rpm. One equation to calculate the tuning speed is as follows:
N_ =(30-a/2~)-{[(A-B+A+ 1)_(A-B+A+ 1)2-4A-B]/[2-A-B-Ll-Cl]}0.5 Where:
N+=tuned engine speeds A=(l2-A~ l-A2) Al=cross sectional area of runner ll=rli~t~nre from intake valve to plenum A2=cross sectional area of plenum 12=~i.ct~nr-e from plenum to throttle body inlet B=C2/Cl Cl =Veff=D-(CR+ 1)/[2-(CR-l)]
D=displacement per cylinder CR.=co~ ssion ratio C~=volume from throttle body inlet to intake valve (ll-Al) a=speed of sound in air (mixture) Ll = ll-Al ~sllmP-s runners are of approximately equal length and volume adapted from Heywood, 1988, p.312-313.
In the lowest cost embodiment, manifold heating is provided by an engine coolant jacket. Notably, only enough heat should be added to vaporize any residual liquid fuel. Any heat above that amount merely increases the intake charge temperature, reducing its peak power output. Accordingly, the trend is to minimi7f manifold heating. Figures 6a, 6b, and 6c depict three options for the coolant jacket 5 approach to heating the plenum. Figure 6a shows a Illi~illllllll approach wherein the coolant jacket ~ulloullds the vertical portion of the plenum (19) and also underlies the floor of the plenum (20). Figure 6b shows an option wherein the jacket is extended to also include the floor (22) and vertical wall portions (21) of the branches. Figure 6c shows an extreme case where the coolant jacket also extends beneath the floor10 portion (23) of the runners for their entire length. Figure 7 provides a 3-D cross sectional view of the plenum heating concept from Figure 6a.
As an ~lle..lAIive to coolant heating, electric heating is possible. Both Texas lulllelll~ and GTE Sylvania have produced PTC (positive telllpeldLul~ coefficient) heaters for automotive use. Such heaters typically consist of an electrically heated al lmin-lm body which is mounted in the floor of the manifold casting and is at least partially thermally isolated from the casting by g~ ting or other in~lllAtQr means.
Such devices have had in-rush power levels > 700 watts and quiescent power levels > 170 watts. PTC heaters, although more e~el~iv~, can have source telllpeldlul~sof 175C, and thus are excellent ~ IIIAI;V~S for assuring fuel vaporization.
A fundamental feature of this invention is the staging of airflow out of the plenum and into the runner conduits. Consider that the plenum has a left (L) andright (R) half as shown in Figure 8. Also note that most 4-cylinder engines have a firing order, and hence a breathing sequence, of 1-3-4-2. Thus, the air will flow out of the plenum in the following sequence: L-R-L-R. Hence, the flow symmetrically switches back and forth between the two sides of the plenum, at the same frequency as the intake pulses occur. For purposes of illustrating the concept, the firing order 1-34-2 is used in the following examples. However, the concept also applies to the less frequently used firing order 1-2-4-3.
It is also worthwhile to note the sources of peak, i~l~lA~ ous intake flow.
Figure 9 graphically depicts the sources of peak airflow, showing the condition where Cylinder 2 is bl~,alllillg and the other three cylinders have closed intake valves. Peak flow (26) is composed of the main airflow (24) coming past the throttle, plus stored -air (25) that is released from the dead-headed runner conduits (i.e. runner conduits conn~ctecl to cylinders with closed intake valves). Two points are notable. Firstly, the vectors of the various flow components all tend to be in the direction of enhancing airflow into the active runner conduit, and creating only modest turbulence.
5 Secondly, since the manifold is symmetrical, identical vector condition exists regardless of which cylinder is b~ea~ g (i.e. while vectors are mirror images, their amplitudes and relative relationships are unchanged). Thus, this concept is particularly stable and prone to equal distribution.
TEST RESULTS
An intake manifold in accordance with this invention has been designed, cast, and tested on a production 2.5L, 4-cylinder TBI engine. Air-fuel distribution was measured at 54 speed-load points and wide open throttle power measured at 17 points (2000 to 5200 rpm), with two air cleaner configurations. The manifold in accordance with this invention provided more power, at all speeds, than the original equipment 15 manifold. The data from those tests, along with the design features of the present invention, are co,l~aled to conventional manifold designs in the discussion below.
Specifically, the intake manifold of this invention is compared to two conventional manifold design styles as used on three production engines. The two conventional design styles are referred to as TRI-Y manifolds (two reviewed) and 4-20 LEG manifolds (one reviewed). The table below co",p~,~s manifold features. It is notable that all used throttle body fuel injection and were offered on recent, high volume North American 4-cylinder engines.
Pro~h~ti~n Fn~n~ ~ Manifold Details M~mlfaçtllrer General MotorsFord Chrysler Part No. 10124608RF-E7EE-9425-JC 4621360 Engine size(cc's) 25001 2500' 1900 2200 Power (~rpm) ~ +5% 92 ~ 440088 ~ 4400 93 ~ 5200 30 Specific Power (BHP/L) 36.8 46.3 42.3 Plenum:Vol (cc's) 246 246 254 604 21 G~39~
Plenum:Eng.Vol 9.8% 9.8% 13.4% 27.5%
Manifold Vol (cc's) 1594 1220 700 1040 Manifold:Eng.Vol 63.8% 48.8% 36.8% 47.3%
Runner Conduits Lengths: 1 12.5 5.0 6.13 4.0 (ininches) 2 12.5 5.0 3.38 4.5 3 12.5 5.0 3.38 4.5 4 12.5 5.0 6.13 4.0 Runner Conduit Equivalent Dia.
(in) 1.445 1.445 1.37 1.641 Runner Vol.(cc's) 1348 522 446 436 Notel: same 2500 cc engine As can be seen, the size of the runner conduits, plenums and overall manifolds varied signifi~ntly, in both absolute terms and as pelcelllage of engine swept volume (36.8% to 48.8%). Specific power output also varied widely (36.8 to 46.3 BHP/L).However, as can be seen from the curves shown in Figures lOa through lOe, there is no obvious correlation between intake manifold design factors and specific power 20 output. The exception is that use of the present design produced higher specific power output. The characteristics plotted in Figure 10 are as follows:
Figure Feature Plotted versus BHP/L
Figure lOa Manifold Volume + Engine Volume Figure lOb Plenum Volume + Engine Volume 25Figure lOc Runner Volume + Engine Volume Figure lOd Runner Conduit Length Figure lOe Equivalent Runner Diameter Although the data sample is ~-lmitte(1ly quite limit~d, the curves in Figure 10 in(lic~te that conventional manifold design features have no obvious, strong 30 correlation with specific power output. In fact, one would expect specific power output to show a strong correlation with other factors such as c~m~h~ft lift, c~m~h~ft event duration, c~m~h~ft overlap, peak power rpm, intake valve size, number of 216939~
intake valves, and compression ratio. Notably, while the present manifold's design feature did not seem to fit any possible trends from these three engines, it did produce more power. The obvious suggestion is that the present design approach is fundamentally dirr~lclll.
Simplified, 2-D top views of the three manifold designs are provided in Figures 1 la to 11c. All are shaded to identify left and right halves of the manifolds.
These views help illustrate the blcaLl~illg dirrelcl~es between the manifold types.
Notably, conventional manifolds pair cylinders 1-2 and 3-4 together, while the present manifold pairs 1-4 and 3-2 together. The dirr~lcl1ces in cylinder pairings results in dirrerellL bledLhillg phasings (i.e. the sequence of gases leaving the plenum) as is summarized in the following table:
Airflow to in~ Cyl No.
is drawn from the 1 ~..ul.~'s Left (L) Right (R) Rç~-llt~nt rl~nu"~
Manifold Type Sector Sector Bre~thin~ Order INVENTION 1,4 3,2 L-R-L-R
TRI-Y 1,2 3,4 L-R-R-L
4-LEG 1,2 3,4 L-R-R-L
The plenum breathing characteristics of the three manifold types are graphically portrayed in Figures 12a, 12b, 12c and 12d. They depict the relativelocation of the mass airflow out of the plenums versus engine position (in number of revolutions). Theflow location axes are gra(l~l~te~l from Left to Right, with the full scale span representing a 180 change in angular location (the 0 2 180 line defines the throttle plate centerline). While the graphs are based on a simplified model of engine bleaLlling, they inrlic~te the relative sequencing of manifold ble~Llling.
For r~fe~ ce purposes, Figure 12a shows that four intake pulses occur every two engine revolutions. Figure 12b illustrates that the present manifold's plenum has a symmetrical breathing sequence which switches sides (L-R-L-R-...) synchronously 30 with the engine's breathing sequence (1-3-4-2). By comparison, the TRI-V
manifold's b~Llling sequence (Figure 12c) is symmetrical, but switches sides at half the synchronous rate (i.e., every other intake pulse). The 4-LEG manifold's 21693g~
b,eaLhil1g sequence (Figure 12d), while superficially symmetrical (R-R-L-L-R-R-L-L-...) has flow occurring from four different angular locations and is more accurately labelled as asymmetrical. The symmetrical and synchronous nature of the present manifold breathing sequence are considered to increase stability and tuning efficiency.
The present design is also regarded as being superior at sourcing a portion of its peak in~t~nt~nPous flow from the dead-headed runner conduits. The sources ofpeak flow are illustrated in Figures 13a, 13b, and 13c. In the case of the TRI-Ymanifold (Figure 13a), dead-headed gases from cylinders 3 and 4 (29,28) combine to reinforce the main air flow past the throttle (24), which is then partially opposed by the gas from de~dhP~ded cylinder 1 (27). In the case of the 4-LEG manifold (Figure 13b), dead-headed gases from cylinders 1 and 3 (27,29) primarily oppose the mainair flow past the throttle (24), while the gas from dead-headed cylinder 4(28) primarily ~cillro~;es the main flow (24). In the case of the present design (Figure 13c), dead-headed gases from cylinders 1 and 4 (27,28) combine to reinforce the main air flow past the throttle (24), which is then malgil~lly reinforced by the gas from ~e~dhPaded cylinder 3 (29).
While turbulence is desirable from the standpoint of causing the air and fuel to mix, it is undesirable as it causes flow losses. Accordingly, intake manifolds must balance turbulence and airflow. The present manifold is deemed to offer a lower and particularly stable amount of turbulence which can be adjusted by the geometry of the individual design (e.g., convergence angle of the runner at the branch junc~ulcS 17 and 18).
By comparison, the conventional designs tend to have the flow from one or more of the d~P~llhe~d~Pd runner conduits m~rke-lly opposing the flow into the active runner conduit. While this opposition may create turbulence which assists in mixing, it would also act to reduce the manifold's flow efficiency.
While one embodiment of this invention has been illustrated in the acco",pa,lyillg drawings, and described hereinabove, it will be evident to those skilled in the art that changes and modifications may be made therein without departing from the essence of this invention, as set forth in the appended claims.
1~9 ~a~ 1 3 IS ~ c
Claims (12)
1. A tuned intake manifold for Otto cycle engines, comprising:
a plenum, an aperature in the plenum through which the plenum can receive a gaseous fuel mixture, first and second branch openings into the plenum, the openings being disposed in substantial opposition to each other across the plenum, first and second branch conduits communicating with said first and second branch openings respectively, each branch conduit divaricating into a plurality of runner conduits all of which terminate at their connections to a head flange; the various gaseous paths, each defined by one of the branch conduits and one of the runner conduits into which the branch conduit divaricates, all having substantially the same length beginning at the plenum, substantially the same volume, and substantially the same radius and arc-length of curvature.
a plenum, an aperature in the plenum through which the plenum can receive a gaseous fuel mixture, first and second branch openings into the plenum, the openings being disposed in substantial opposition to each other across the plenum, first and second branch conduits communicating with said first and second branch openings respectively, each branch conduit divaricating into a plurality of runner conduits all of which terminate at their connections to a head flange; the various gaseous paths, each defined by one of the branch conduits and one of the runner conduits into which the branch conduit divaricates, all having substantially the same length beginning at the plenum, substantially the same volume, and substantially the same radius and arc-length of curvature.
2. The tuned intake manifold claimed in claim 1, for use with a four-cylinder engine, wherein each branch conduit divaricates into two runner conduits, the runner conduits for the first branch conduit carrying fuel mixture to cylinders 1 and 4, the runner conduits for the second branch conduit carrying fuel mixture to cylinders 2 and 3.
3. The tuned intake manifold claimed in claim 2, in which the four-cylinders are in line and fire in one of the sequences: 1, 3, 4, 2 or 1, 2, 4, 3, and wherein the head flange connections are in uniformly spaced-apart rectilinear alignment, and in which the plenum is adapted to be located in spaced relation from the head flange and symmetrically with respect to the said connections, with the first branch conduit projecting toward the head flange and the second branch conduit projecting away from the head flange, the runner conduits from said first branch conduit each undergoing an S-curve, the runner conduits from said second branch conduit each undergoing a J-curve.
4. The tuned intake manifold claimed in claim 3, in which heat is applied to theplenum to ensure vaporization of any liquid fuel entering the plenum.
5. The tuned intake manifold claimed in claim 3, in which the plenum is substantially cylindrical, and in which said first and second branch openings are located at opposed ends of a diameter.
6. The tuned intake manifold claimed in claim 2, in combination with a four-cylinder engine which fires in-line cylinders in one of the sequences: 1, 3, 4, 2 or 1, 2, 4, 3.
7. The tuned intake manifold claimed in claim 3, in combination with a four-cylinder engine which fires in-line cylinders in one of the sequences: 1, 3, 4, 2 or 1, 2, 4, 3.
8. The tuned intake manifold claimed in claim 4, in combination with a four-cylinder engine which fires in-line cylinders in one of the sequences: 1, 3, 4, 2 or 1, 2, 4, 3.
9. The tuned intake manifold claimed in claim 5, in combination with a four-cylinder engine which fires in-line cylinders in one of the sequences: 1, 3, 4, 2 or 1, 2, 4, 3.
10. The tuned intake manifold claimed in claim 2, in combination with a vehicle powered by a four-cylinder engine which fires in-line cylinders in one of the sequences: 1, 3, 4, 2 or 1, 2, 4, 3.
11. A method for delivering a gaseous fuel mixture to the cylinders of an engine, having at least four in-line cylinders, the number of cylinders being even, comprising:
receiving the mixture in a plenum through an aperture, passing the mixture out of the plenum through first and second branch openings disposed in substantial opposition to each other across the plenum, passing the mixture into first and second branch conduits communicating with said first and second branch openings respectively, each branch conduit divaricating into a plurality of runner conduits all of which terminate at their connections to the engine; and ensuring that the various gaseous paths, each defined by one of the branch conduits and one of the runner conduits into which the branch conduit divaricates, all have substantially the same length beginning at the plenum, substantially the same volume, and substantially the same radius and arc-length of curvature.
receiving the mixture in a plenum through an aperture, passing the mixture out of the plenum through first and second branch openings disposed in substantial opposition to each other across the plenum, passing the mixture into first and second branch conduits communicating with said first and second branch openings respectively, each branch conduit divaricating into a plurality of runner conduits all of which terminate at their connections to the engine; and ensuring that the various gaseous paths, each defined by one of the branch conduits and one of the runner conduits into which the branch conduit divaricates, all have substantially the same length beginning at the plenum, substantially the same volume, and substantially the same radius and arc-length of curvature.
12. The method claimed in claim 11, wherein each branch conduit divaricates intotwo runner conduits, the runner conduits for the first branch conduit carrying fuel mixture to cylinders 1 and 4, the runner conduits for the second branch conduit carrying fuel mixture to cylinders 2 and 3.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US08/393,682 | 1995-02-24 | ||
| US08/393,682 US5551387A (en) | 1995-02-24 | 1995-02-24 | Tuned intake manifold for OTTO cycle engines |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2169398A1 true CA2169398A1 (en) | 1996-08-25 |
Family
ID=23555796
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002169398A Abandoned CA2169398A1 (en) | 1995-02-24 | 1996-02-13 | Tuned intake manifold for otto cycle engines |
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| Country | Link |
|---|---|
| US (1) | US5551387A (en) |
| CA (1) | CA2169398A1 (en) |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB9702028D0 (en) * | 1997-01-31 | 1997-03-19 | Perkins Ltd | Inlet manifold for an internal combustion engine |
| GB2338987A (en) * | 1998-06-30 | 2000-01-12 | Cummins Engine Co Ltd | I.c. engine intake air system with electric heater inside manifold |
| US6202627B1 (en) * | 1998-08-05 | 2001-03-20 | Honda Giken Kogyo Kabushiki Kaisha | V-type multi-cylinder internal combustion engine |
| KR100331454B1 (en) * | 1998-09-01 | 2002-04-09 | 신구 이이치 | Inertia charge intake manifold for multi-cylinder internal combustion engine and connecting method for branch pipes of intake manifold |
| JP2000199461A (en) * | 1998-12-29 | 2000-07-18 | Suzuki Motor Corp | Intake system of internal combustion engine |
| US6755897B2 (en) * | 2002-10-23 | 2004-06-29 | Siemens Vdo Automotive Inc. | Constant velocity radial inflow particle separator |
| US7066129B2 (en) * | 2003-10-06 | 2006-06-27 | General Motors Corporation | Intake manifold and runner apparatus |
| KR101610164B1 (en) * | 2014-11-26 | 2016-04-08 | 현대자동차 주식회사 | Intake system |
| KR101637297B1 (en) * | 2014-12-09 | 2016-07-07 | 현대자동차 주식회사 | Intake system |
| JP7121192B2 (en) * | 2019-04-24 | 2022-08-17 | ヤマハ発動機株式会社 | straddle-type vehicle |
| CN114215668B (en) * | 2021-11-30 | 2022-12-20 | 陕西柴油机重工有限公司 | Layout method for controlling air pipeline by marine diesel engine |
Family Cites Families (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE2060740C3 (en) * | 1970-12-10 | 1974-10-10 | Ludwig 8543 Hilpoltstein Elsbett | Method for influencing the rotating layers of air in the cylinder or combustion chamber of an air-compressing multi-cylinder reciprocating internal combustion engine and device for carrying out the method |
| DE2311636A1 (en) * | 1973-03-09 | 1974-11-21 | Awtomobilnij Sawod Im Leninsko | INTAKE LINE FOR FOUR CYLINDER COMBUSTION IN-LINE ENGINES |
| US4501235A (en) * | 1983-04-04 | 1985-02-26 | Ford Motor Company | Tuned engine intake manifold |
| JPS60222523A (en) * | 1984-04-19 | 1985-11-07 | Mazda Motor Corp | Suction device of engine |
| US4760819A (en) * | 1987-07-16 | 1988-08-02 | Vorum Peter C | Short pipe manifold for four-stroke engines |
| DE3742057C1 (en) * | 1987-12-11 | 1988-09-22 | Porsche Ag | Intake system for a multi-cylinder internal combustion engine |
| GB2252791A (en) * | 1991-02-16 | 1992-08-19 | Ford Motor Co | I.c. engine inlet manifold |
| GB2256675A (en) * | 1991-06-11 | 1992-12-16 | Ford Motor Co | Tuned i.c.engine intake system. |
-
1995
- 1995-02-24 US US08/393,682 patent/US5551387A/en not_active Expired - Fee Related
-
1996
- 1996-02-13 CA CA002169398A patent/CA2169398A1/en not_active Abandoned
Also Published As
| Publication number | Publication date |
|---|---|
| US5551387A (en) | 1996-09-03 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| FZDE | Discontinued |